CHAPTER IV 



VAKIATION OF DOMESTICATED ANIIVIALS AND 

 CULTIVATED PLANTS 



The facts of variation and artificial selection — Proofs of the generality of 

 variation — Variations of apples and melons — Variations of flowers — 

 Variations of domestic animals — Domestic pigeons — Acclimatisation 

 — Circumstances favourable to selection by man — Conditions favour- 

 able to variation — Concluding remarks. 



Having so fully discussed variation under nature it will be 

 unnecessary to devote so much space to domesticated animals 

 and cultivated plants, especially as Mr. Darwin has published 

 two remarkable volumes on the subject where those who 

 desire it may obtain ample information. A general sketch of 

 the more important facts will, however, be given, for the 

 purpose of shoAving how closely they correspond "svith those 

 described in the jDreceding chapter, and also to point out the 

 general principles which they illustrate. It will also be 

 necessary to explain how these variations have been increased 

 and accumulated by artificial selection, since we are thereby 

 better enabled to understand the action of natural selection, to 

 be discussed in the succeeding chapter. 



The facts of Variation and Artificial Selection. 



Every one knows that in each litter of kittens or of 

 puppies no two are alike. Even in the case in Avhich several 

 are exactly alike in colours, other differences are always 

 perceptible to those who observe them closely. They will 

 differ in size, in the proportions of their bodies and limbs, in 

 the length or texture of their hairy covering, and notably 

 in their disposition. They each possess, too, an individual 



